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PROGRESS REPORTS - U.S. Fish and Wildlife Service · PDF file PROGRESS REPORTS 2016 FISH DIVISION Oregon Department of Fish and Wildlife Clackamas River Bull Trout Reintroduction Project:

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  • PROGRESS

    REPORTS 2016

    FISH DIVISION

    Oregon Department of Fish and Wildlife

    Clackamas River Bull Trout Reintroduction Project:

    Monitoring bull trout with census redd counts and PIT tag technology, 2011-2016

  • Oregon Department of Fish and Wildlife prohibits discrimination in all of its programs and services on the basis of race, color, national origin, age, sex or disability. If you believe that you have been discriminated against as described above in any program, activity, or facility, or if you desire further information, please contact ADA Coordinator, Oregon Department of Fish and Wildlife, 4034 Fairview Industrial Drive SE, Salem, OR 97302, 503-947-6200.

  • Clackamas River Bull Trout Reintroduction Project:

    Monitoring bull trout with census redd counts and

    PIT tag technology, 2011-2016

    Steve Starcevich, ODFW Native Fish Investigations Program

    Corvallis Research Lab, December, 2016

    Abstract

    Bull trout were extirpated from the Clackamas River basin by the 1960s. A reintroduction

    feasibility assessment and an implementation plan were completed in 2007 and 2011, respectively,

    with the goal of establishing a self-sustaining population of 300-500 adults in the Clackamas River

    basin. Phase one of the project (2011-2016) involved translocating 2,868 bull trout (80% as age-1

    and 2) from the Metolius River basin, tagging each with a passive integrated transponder (PIT tag),

    releasing them in the upper Clackamas River basin, and monitoring them using a variety of

    methods. Monitoring methods included census redd counts and detection of PIT-tagged bull trout

    at a PIT detection site in Pinhead Creek. The number of redds observed and adult PIT-tagged bull

    trout (defined as age-5 and older) detected have steadily increased from 18 redds and 15 adults in

    2013 to 68 redds and 72 adults in 2016. There was a strong linear relationship between the annual

    redd count and the number of adults detected in Pinhead Creek, suggesting that redd counts may

    be useful in tracking trend in adult abundance. In 2016, adults detected in Pinhead Creek were

    translocated mainly at age-1 and 2 (i.e., 70-210 mm), released at locations both in Pinhead Creek

    and the Clackamas River, and spent a median of 26 d in Pinhead Creek during the spawning period.

    The second phase of the project begins in 2017 and entails continued monitoring of progress

    toward the reintroduction goal, at least in part through census redd surveys and the use of PIT tag

    technology, of producing naturally-reproducing, self-sustaining population of bull trout in the

    Clackamas River basin.

  • 2

    Introduction

    Bull trout (Salvelinus confluentus) were extirpated from the Clackamas River basin by the 1960s.

    A feasibility assessment (Shively et al. 2007) and an implementation plan (US Fish and Wildlife

    Service [USFWS] 2011) for bull trout reintroduction were completed with the goal of establishing

    a self-sustaining population of 300-500 adult in Clackamas River basin. The reintroduction was

    divided into three phases of approximately 6-7 years each (USFWS 2011). The first phase was

    from 2011-2016 and involved translocating 2,868 bull trout from the Metolius River basin (Table

    1), giving each one a unique passive integrated transponder (PIT tag), releasing them at various

    locations and lifestages (80% of which were between 70-250 mm total length) in the upper

    Clackamas River basin, and then monitoring them using radio telemetry, PIT tags, electrofishing,

    and redd surveys. The second phase begins in 2017 and entails continued monitoring of progress

    toward the reintroduction goal, at least in part through census redd surveys and the use of PIT tag

    technology.

    Redd surveys from 2011 to 2014 were conducted by an ad hoc multi-agency group of observers.

    In 2015 and 2016, census redd surveys were conducted by a crew of five experienced observers

    from the Oregon Department of Fish and Wildlife (ODFW), with additional help from other

    agencies and volunteers. In 2015, a long interval (44 d) between censuses may have increased

    uncertainty and observer error in identifying new bull trout redds and discerning them from redds

    constructed during a previous season or by other fall-spawning fish species such as Chinook

    salmon (Oncorhynchus tshawytscha) or coho salmon (O. kisutch). In 2016, the objectives were to

    1) evaluate the effectiveness of a two-week interval between each census conducted throughout

    the potential spawning period, 2) use thermographs to refine the sampling frame and focus surveys

    in thermal habitat suitable for bull trout spawning, 3) examine relationships between redd counts

    and PIT-tagged bull trout detected in the Pinhead Creek watershed, and 4) characterize the spatial

    and temporal distribution of salmon spawning.

    Methods

    Census redd surveys

    A five-person crew conducted census redd surveys in all potential bull trout spawning habitat in

    the upper Clackamas River and major tributary basins (Figure 1). Census surveys were generally

    completed every two weeks (Table 2). The first census survey was conducted in mid-August, prior

    to the putative start of bull trout and Chinook salmon spawning. This survey was used to

    familiarize the field crew with bull trout redd identification by analyzing characteristics of old

    redds from a previous season (i.e., redds constructed prior to August) and flagging areas that could

    be mistaken for new redds. A new bull trout redd was identified by its pocket-mound structure,

    smaller gravel size relative to substrate in Chinook salmon redds, and the contrast of brighter

    disturbed gravel relative to darker surrounding substrate matrix. Chinook and coho salmon redds

    were distinguished by larger dimensions and substrate size and by identifying the species of adult

    salmon occupying a redd. The crew flagged new bull trout redds and recorded the following data:

    GPS location, maximum length and width, species and number of adults occupying redd, and brief

    descriptions of observer certainty.

  • 3

    Table 1. PIT-tagged bull trout translocated from the Metolius River basin to the Clackamas River basin in

    the first phase of the reintroduction project. Lifestages were defined by the size classes 70-250 mm

    (juvenile), 251-450 mm (subadult), 451-650 mm (adult).

    Lifestage Date

    Year Location Juvenile Subadult Adult Min Max

    2011 Clackamas River 0 0 11 30-Jun 30-Jun

    Clackamas River 1 0 14 3 30-Jun 30-Jun

    Clackamas River 2 0 11 21 30-Jun 15-Jul

    Last Creek 42 0 0 30-Jun 15-Jul

    Pinhead Creek 16 0 0 21-Jul 21-Jul

    2011 Subtotal 58 25 35

    2012 Clackamas River 1 0 9 1 14-Jun 14-Jun Clackamas River 2 2 34 16 14-Jun 12-Jul Last Creek 151 0 0 3-May 28-Jun Pinhead Creek 364 0 0 10-May 31-May

    2012 Subtotal 517 43 17

    2013 Clackamas River 3 30 3 6-Jun 13-Jun

    Clackamas River 1 0 60 5 6-Jun 27-Jun

    Last Creek 338 0 0 11-Apr 27-Jun

    Pinhead Creek 283 0 0 2-May 30-May

    2013 Subtotal 624 90 8

    2014 Berry Creek 296 0 0 24-Apr 29-May Clackamas River 1 26 45 7 5-Jun 25-Jun 2014 Subtotal 322 45 7

    2015 Berry Creek 287 1 0 10-Apr 5-Jun

    Clackamas River 1 13 73 7 15-May 5-Jun

    2015 Subtotal 300 74 7

    2016 Clackamas River 1 95 94 6 20-May 13-Jun Clackamas River 5 501 0 0 8-Apr 13-May 2016 Subtotal 596 94 6

    Total 2417 371 80

    Grand total 2868

    Salmon redds generally were not treated individually, except in Pinhead Creek and Last Creek,

    where they were treated like bull trout redds. Elsewhere, the crew usually recorded the number of

    salmon redds tallied over 100-300 m survey sections and a GPS location for each section mid-

    point.

    Bull trout and salmon redd data were entered in an Access database that contains data from

    previous bull trout spawning surveys in the upper Clackamas River basin. Each year spawning

    surveyors recorded observations of some bull trout redds described as “potential”, “possible”,

    “likely”, “test dig?” or some other variant registering uncertainty in their observations; these

    descriptions were included in the database. In 2015 and 2016, observers were trained to include a

  • 4

    Figure 1. Survey extent, potential natural fish barriers, and salmon and bull trout redds observed during

    census redd surveys in the upper Clackamas River basin. Each bull trout and coho salmon marker represents

    a single observed redd. Chinook salmon redds were not individually georeferenced, thus an individual

    Chinook marker may represent multiple redds (range, 1-30 redds) counted over a survey extent (range, 100-

    200m). Secondary channels are not shown and redd markers have not been snapped to the stream line.

  • 5

    Table 2. Census survey schedule and reaches and the number of bull trout redds counted in each census.

    Some reaches were not surveyed (NS) in each census.

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